Data too large for tiny index in Kibana

Elastic Stack Elasticsearch
1

I have a tiny index (400kB) that I try to do "Discover" on in Kibana. It gives me the error:
Data too large, data for [TimestampUtc] would be larger than limit of [2508954009/2.3gb]]

How can this be? I'm currently increasing the cluster size to overcome this, but there seems to be no reason to use over 2,3gb to store 800 documents...

Cluster 376b3a

2

It probably means fielddata, is that field analysed in your mappings?

3

Thank you for your answer.

No, it is just a date field, not analyzed:

"TimestampUtc": {
"type": "date",
"format": "epoch_millis||dateOptionalTime"
},

But even if it was, 400kb of data could not fill 2,3gb?